Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations that may be located onshore or offshore. The development of subterranean operations and the processes involved in removing hydrocarbons from a subterranean formation are complex. Typically, subterranean operations involve a number of different steps such as, for example, drilling a wellbore at a desired well site, treating the wellbore to optimize production of hydrocarbons, and performing the necessary steps to produce and process the hydrocarbons from the subterranean formation.
When performing subterranean operations, it is often desirable to obtain information about the formation.
The basic techniques for electromagnetic logging for earth formations are well known. For instance, induction logging to determine resistivity (or its inverse, conductivity) of earth formations adjacent a borehole has long been a standard and important technique in the search for and recovery of hydrocarbons. Generally, a transmitter transmits an electromagnetic signal that passes through formation materials and induces a signal in one or more receivers. The properties of the signal received, such as its amplitude and/or phase, are influenced by the formation resistivity, enabling resistivity measurements to be made. The measured signal characteristics and/or formation properties calculated therefrom may be recorded as a function of the tool's depth or position in the borehole, yielding a formation log that can be used to analyze the formation.
Electronic sensors, such as sensors used for electromagnetic logging for earth formations, often benefit from a magnetic shield, which protects them from magnetic and electromagnetic effects that may interfere with sensor function. The benefits of magnetic shields increase with the sensitivity of the shielded sensor.
Metals are often a component of magnetic shields, due to their inherent abilities to block or dampen magnetic effects. Shields formed entirely or largely from metal, however, may not provide additional benefits in some applications.
For example, in the conditions found downhole, magnetic shields formed entirely or largely from metal cannot be used between as structural component and a non-structural component and cannot be used as a vibration damper because of the high stiffness of such shields.
Multi-functional magnetic shields are needed for downhole logging operations.